Disclosed is a heat-sensitive processless planographic printing plate material containing a thermosensitive protection layer. The planographic printing plate material sequentially comprises a supporting body, a hydrophilic layer, a heat-sensitive layer and a thermosensitive protection layer from the bottom up. The thermosensitive protection layer therein can not only isolate oxygen and protect the heat-sensitive layer from oxygen inhibition, but can also sense heat and allow a polymerization reaction to take place. Thus the binding force between same and the next layer is improved, so that the precision of printing plate images is high, the development performance is good, and the pressrun is high.

A polymerizable composition is provided, including an infrared absorber, a polymerization initiator, a polymerizable compound, and a polymer binder, wherein the polymer binder is a particulate random copolymer, and the polymer binder has structural units derived from a polymerizable polyalkylene oxide-based monomer and a polymerizable nitrogen-free non-polyalkylene oxide-based monomer. The polymerizable composition may be used in the production of imageable elements or printing plates.

An original plate for forming an ink film includes a surface layer including a stimulus-responsive compound which responds to an external stimulus to have reversibly changed affinity with water; and a resin.

Provided are a thermal fusion-type lithographic printing plate precursor in which the visibility is excellent, ablation during laser exposure is suppressed, and the contamination of dampening water and printing ink during on-machine development is suppressed by a lithographic printing plate precursor having a support and an image-recording layer, in which the image-recording layer is capable of forming an image by infrared laser exposure, a non-exposed portion of the image-recording layer is removable by at least one of dampening water and printing ink on a printer, and the image-recording layer contains (1) a color developing system in which a hue change generated by infrared laser exposure is a/b0.6 and (2) 70% by mass or more of a thermoplastic polymer particle with respect to a solid content of the image-recording layer and a plate-making method in which the thermal fusion-type lithographic printing plate precursor is used.

The invention relates to an imageable coating layer, thermal negative-working lithography printing plate, and platemaking method. The coating layer includes constituents in parts by weight: a radically polymerizable compound 20-60 parts, a radiation-absorbing compound 0.5-12 parts, a free radical initiator 1-25 parts, a binding agent 10-70 parts, and a development accelerator 0.5-15 parts. The platemaking method includes the steps: S1, preparing a printing plate precursor that includes a substrate having a hydrophilic surface or is provided with a hydrophilic layer and imageable coating layer covering the substrate; S2, patternedly exposing the printing plate precursor, forming an exposed area and an unexposed area; and S3, removing the unexposed area via a development process. The employment of the imageable coating layer and the plate making method allows the implementation of a flexible development process of on-press development or off-press development and produces a printing plate provided with great printing performance.

Provided are a positive type planographic printing plate precursor including: a support which has a hydrophilic surface; and an image recording layer on the support, the image recording layer containing: a polymer compound 1 having at least one bond selected from the group consisting of a urea bond, a urethane bond, and a carbonate bond in a main chain and containing a sulfonamide group in the main chain; a polymer compound 2-1 having at least one of a constitutional unit represented by Formula S-1 or a constitutional unit represented by Formula S-2 or a polymer compound 2-2 having a constitutional unit represented by Formula EV-1 and a constitutional unit represented by Formula EV-2; and an infrared absorbent, and a method of producing a planographic printing plate obtained by using the positive type planographic printing plate precursor.

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A curable composition includes an infrared absorber having at least one element in Group XIII of the periodic table on a mother nucleus structure and having a chain-like polymethine structure, in which two or more hetero atoms are bonded to carbon atoms at non-meso positions. Also, a lithographic printing plate precursor in which the curable composition is used, and a method for producing a lithographic printing plate in which the lithographic printing plate precursor is used are provided.

The present invention provides an on-press development type lithographic printing plate precursor including, in the following order, a support, an image-recording layer, and a protective layer, in which the image-recording layer contains a) a polymerizable compound, b) an infrared absorber, c) a polymerization initiator, and d) a color forming substance precursor, and the protective layer contains an ultraviolet absorber, and a method of preparing a printing plate.

The present invention aims at providing a lithographic printing plate precursor, a lithographic printing plate manufacturing method, a printing method and an aluminum support manufacturing method that enable the resulting lithographic printing plate to have a long tiny dot press life. The lithographic printing plate precursor of the invention is a lithographic printing plate precursor having an aluminum support and an image recording layer disposed above the aluminum support. When measured over a 400 m400 m region of a surface of the aluminum support on the image recording layer side using a three-dimensional non-contact roughness tester, pits with a depth from centerline of at least 0.70 m are present at a density of at least 3,000 pits/mm.sup.2; and a surface area ratio S is not less than 35%, the surface area ratio S being determined using an actual area S.sub.x obtained, through three-point approximation, from three-dimensional data acquired by measurement at 512512 points in 25 m square of the surface of the aluminum support on the image recording layer side by means of an atomic force microscope and a geometrically measured area S.sub.o.

Negative-working, radiation-sensitive printing plates include or consist of a hydrophilic first layer or substrate and, thereover, an oleophilic imaging layer that includes an iodonium borate free-radical initiators in accordance herewith have the structure

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where X and Y are alkoxy, p and q range independently from 0 to 5, and p+q5; or p and q may range independently from 0 to 4, with p+q4.